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Liquid Air Energy Storage: A Sustainable Solution for Long-Duration Grid Needs
As global efforts intensify to minimize carbon emissions, renewable energy sources like solar and wind are becoming increasingly vital for electricity grids. However, these renewable sources generate power only during favorable weather conditions. To maintain a reliable power supply that operates around the clock, effective energy storage solutions are essential to capture excess electricity during peak generation and deliver it when needed. Some situations may require storing electricity for extended periods, ranging from hours to days or even longer.
Challenges of Traditional Energy Storage Methods
One promising method for long-duration energy storage is pumped hydro storage. This technique involves transferring water from a lower reservoir to a higher one when there’s surplus electricity. When demand rises, the water is released back down to generate power through turbines. However, this approach is geographically limited and many potential sites in the U.S. are already utilized.
Lithium-ion batteries provide a viable option for grid-scale storage, but they typically offer discharge capabilities for only about four hours. Prolonged storage requirements can lead to significant costs.
Innovative Liquid Air Energy Storage (LAES)
Researchers from MIT and the Norwegian University of Science and Technology (NTNU) are exploring an innovative alternative: liquid air energy storage (LAES). This concept involves cooling ambient air until it liquefies, enabling large-scale energy storage.
LAES systems are technically feasible, environmentally friendly, and can be deployed in diverse locations. They have the potential to store electricity for days and release it as needed. However, assessing their economic viability has been a challenge.
Supported by funding from the MIT Energy Initiative’s Future Energy Systems Center, the researchers developed a model to analyze the economic feasibility of LAES under various future energy scenarios aligned with decarbonization goals.
Their analysis indicated that LAES could be economically viable in select locations under certain scenarios. Policies providing subsidies on capital expenditures significantly enhance its economic appeal compared to traditional storage methods like pumped hydro and lithium-ion batteries.
LAES technology represents a promising solution to achieve sustainable, reliable energy storage that aligns with future decarbonization goals.
How LAES Systems Work
- Charging: The system is charged when electricity supply exceeds demand, causing air to be drawn in and liquefied.
- Storing: The liquid air is stored in highly insulated tanks at low temperatures.
- Discharging: When electricity is needed, the liquid air is pressurized and heated, converting it back into gas. This high-pressure gas expands through a turbine, generating electricity for the grid.
Figure 1. Insulated tanks used for storing liquid air in LAES systems.
- LAES is a clean technology that only uses ambient air and electricity, resulting in zero contaminants.
- The components required for LAES are widely available and do not rely on rare materials.
- It can be installed almost anywhere, including near industrial processes that produce waste heat or cold.
Economic Viability and Market Potential
To determine if LAES systems would attract investors, researchers calculated their net present value (NPV), considering all future cash flows including revenues and expenses over the project’s lifespan.
The study included detailed modeling of future energy markets and how LAES might compete against other electricity sources during varying demand scenarios.
The findings suggested that under aggressive decarbonization scenarios, particularly in states like Texas and Florida, LAES could become economically viable.
Optimizing Investment Appeal
While enhancing the energy efficiency of LAES did not significantly improve its economic viability, implementing financial incentives such as subsidies on capital costs dramatically improved its attractiveness for investors.
This insight suggests that supportive policies can facilitate the rapid adoption of LAES technology, making it a promising solution for future energy storage needs.
Cost Comparison and Future Outlook
The researchers found that LAES boasts a competitive levelized cost of storage (LCOS) at approximately $60 per megawatt-hour. This figure positions LAES favorably compared to lithium-ion batteries and pumped hydro systems, highlighting its cost-effectiveness in future energy storage applications.
While current investment viability may be limited, the growing demand for grid-scale energy storage solutions emphasizes the need to continue exploring LAES as a potential key player in achieving sustainable energy goals.
